This invention relates to apparatus for regulating the capacity of a tunnelling machine.
A known tunnelling machine has a chassis, an arm pivotally mounted on the chassis about a pivot pin whose axis extends transversely to the axis of the arm, and a rotatable cutting head mounted at the free end of the arm. The cutting head is driven by means of a rotary drive about the axis of the tunnel being formed. Throughout this specification, the term "tunnel" is intended to include a mine gallery or other elongate excavation.
It is possible, with this type of tunnelling machine, to drive a tunnel having a circular and smooth-walled cross-section by making a series of concentric cuts, the centre-points of which are disposed along the axis of the tunnel. In use, efforts are made to make the fullest possible use of the capacity of the cutting head drive, even when the earth or the rock is not of a uniform consistency. Unfortunately, the arm of such a machine (and the bearings supporting the arm) must be extremely robust, heavy and expensive, if the nominal capacity of the cutting head drive is to be fully utilised for all angular positions of the arm. (Tunnelling machines of this type are described in DE-OS No. 2437 683 and DE-OS No. 2437 669).
The aim of the invention is to provide regulation apparatus for a tunnelling machine which enables the capacity of the cutting head drive to be fully utilised, without it being necessary for the arm and its bearings to be of an excessively robust and expensive construction.